Semiconductor wafers have become larger in scale, now with fabrication facilities commonly utilizing 300 mm wafers to be manufactured into semiconductor devices such as integrated circuits. The integrated circuits themselves have become larger in size with increasing circuit densities. As a consequence, the size of particulate contaminants that can destroy a circuit have decreased significantly, and strict particulate control is necessary during all phases of manufacturing, processing, transporting, and storage of semiconductor wafers.
Wafers are commonly stored and transported in sealed front-opening wafer containers that have a door secured by latches on the open front. The door can be typically removed manually or robotically. Such wafer containers are known in the industry as FOUPs, which is an acronym for front-opening unified pod, and FOSBs, an acronym for front-opening shipping box. The doors on these types of containers are operated with robotic interfaces that have precisely positioned keys that insert into the front of the door to operate latching mechanisms to remove and place the door with respect to the container portion.
Wafer container latching mechanisms ideally have certain characteristics. First, it is desirable that they operate reliably and consistently to latch and unlatch the door. Additionally, it is desirable that the latching mechanisms are made and designed so as to emit a minimum of particulates, such as may be generated by sliding contact of parts during operation. It is further desirable that the latch mechanisms are simple to manufacture, assemble, and clean. Moreover, it is desirable that these latching mechanisms operate smoothly with controlled changes in the relative velocities of moving parts. Many typical existing wafer container latching mechanisms exhibit relatively abrupt deceleration of components. For example, in some such mechanisms, moving parts collide with a fixed stop at the limits of travel. The result is impact and vibration that serves to “launch” any particulates that may be resting on surfaces in the container, thereby enabling such particulates to later precipitate onto the wafers causing contamination and damage.
Front opening wafer containers are typically designed to hold 25 wafers in an axially aligned generally parallel spaced apart arrangement. Recently, however, a need has emerged for sealable wafer containers for holding a single wafer. Prior attempts at latching mechanisms for single wafer containers have not been entirely satisfactory. These prior mechanisms may be prone to “launching” of particulates as described above. Also, some prior mechanisms are prone to accidental unlatching or dislodging of the door. Further, it is desirable that the latching mechanisms for these containers be operable with the same robotic equipment as for the larger containers.
What is needed in the industry is a wafer container for a single wafer having a latching mechanism with improved security, velocity control, and vibration characteristics.